The effective delivery of an oral dentifrice and/or medication capable of inhibiting or killing bacteria responsible for dental disease has long been desirable and has been the subject of a substantial amount of research effort. A wide variety of devices, both active and passive, have been developed to accomplish the delivery of dentifrice or medication to the bristles. Such devices have been developed for both manual and power toothbrushes. Manual toothbrushes typically use a hand-operated pump, such as shown in U.S. Pat. No. 4,221,492 to Boscardin et al and 4,013,370 to Gingras, while power toothbrushes use a variety of approaches, including on-board and external active pumping devices, which include various mechanical, pneumatic and hydraulic elements.
Some power toothbrush fluid-dispensing systems use the action of the toothbrush itself to draw a dentifrice from the reservoir to the bristles, such as shown in U.S. Pat. No. 5,309,590 to Giuliani et al. Some representative examples of fluid-dispensing systems for manual and power toothbrushes include U.S. Pat. Nos. 3,547,110 to Balamuth; 5,066,155 to English et al; 5,208,933 to Lustig and 5,062,728 to Kuo.
The reservoir for the dentifrice is typically located either in the handle portion of the toothbrush, such as shown in the '590 patent, or in a separate device, such as shown in the '110 patent. In some cases, the reservoir is disposable, so that when the fluid in the reservoir is depleted, the reservoir itself is discarded and a replacement reservoir is inserted. Such a system is shown in the '370 patent. In other systems, the reservoir is refillable. Typically, the reservoir contains sufficient fluid for a substantial number of individual uses of the fluid dentifrice or medication.
Various systems for dispensing the fluid from the brushhead are also known. In some cases, the fluid is dispensed from a plurality of openings in the brushhead itself, such as shown in the '492 patent, while in other cases, the fluid is dispensed through the bristles themselves, such as shown in U.S. Pat. No. 4,039,261 to Evans.
Fluid-dispensing systems in general, however, have often been difficult to operate, unreliable and expensive. Many such systems are too complex for reliable operation and/or are incapable of working properly, while other systems fail due to clogging of the fluid lines or exit openings, or poor pumping action, among other reasons. Also, it is difficult to design a system with a pump small enough to fit within a typical toothbrush structure. External pumps are often used, which are bulky and expensive. The pump element, whether on-board or external, is typically too complex for sustained, reliable operation, or too expensive to be practical. For all of these reasons, fluid-dispensing systems for both manual and power toothbrushes have not been particularly successful.
Because of the potential benefits, it is desirable to have a fluid-dispensing system in a power toothbrush which is reliable and yet sufficiently simple in design that it is practical to manufacture and maintain.